Reflectance-based monolithic organic pulsemeter device for measuring photoplethysmogram signal

Photoplethysmogram (PPG) signal is an essential bio-signal that can be used for detecting several heart diseases. It has become fundamental to wearable health monitoring devices. The human vital signs, such as heart rate (HR), Oxygen saturation (SpO2) and respiration rate, can be clearly extracted from the PPG signal. In this paper, we applied reflectance pulse measurement method on an organic optoelectronic device to measure the PPG signal. We fabricated a monolithic device, a red (625nm) organic light-emitting diode (OLED) and an organic photodiode (OPD) sensitive at the aforementioned wavelength. The external quantum efficiency (EQE) of the OLED and the OPD were 7% and 47%, respectively. In this work, we utilized a Bluetooth Low Energy (BLE) for sending the measured PPG signal to the central side, desktop computer. The data traffic of the BLE module was 2 kbps at the minimum connection interval 7.5 ms. The reflectance method showed very good results of (1.5) percent error of the heart rate compared to the commercially reference we obtained.